Veg IPM Update: Week Ending 6/07/17

Sweet Corn

European corn borer (ECB) catches have declined somewhat over the past week. As this has happened, feeding signs in NJ sweet corn plantings have increased. Overall, activity is lower than expected this year, likely due to adverse weather conditions. The highest catches remain in southern Hunterdon County (see map at left), with lower activity elsewhere. At present, infestation rates of 30% have been discovered in the Sergeantsville area of Hunterdon County, with rates of 16 – 22% from Somerset through Camden counties. Feeding is likely to be occurring throughout the central and southern counties at this time, and will appear within the next few days in the northernmost areas. Check 5 plants each in 10 random locations for a 50 plant sample. Look for “shot-hole” injury (see top photo at right, ), and consider treating when the number of infested plants in a 50 plant sample exceeds 12%. As infested plants proceed to the pre-tassel stage, live larvae and damage may be found in the emerging tassels (see bottom photo at right). Once plants hit full tassel, ECB larvae will move downward on the stalk and re-enter the plant near the area where ears are forming. This can result in direct injury to the ear. Growers should consider an insecticide application at the full tassel stage to target ECB larvae as they migrate downward. This application can eliminate larvae that have escaped any earlier insecticide applications.

The highest nightly ECB catches for the previous week are as follows:

Allentown 1

Lawrenceville 1

Clinton 1

Little York 1

Denville 1

Medford 1

East Vineland 1

Milford 1

Georgetown 1

Sergeantsville 1

Green Creek 1

South Branch 1

Several corn earworm (CEW) moths were captured in blacklights over the past week. These individuals indicate that there is a low population of this pest in active in NJ. In areas where sweet corn is silking, this is a moderate threat to the crop. At present, the highest activity is along the Atlantic-Camden County border (see CEW map at right).

The highest nightly CEW blacklight trap catches are as follows:

Elm 2

Folsom 1

Downer 1

Medford 1

Eldora 1

Pedricktown 1

The CEW pheromone trap network is currently being deployed in southern NJ. Several of the traps have registered low-to moderate catches, reinforcing the presence of a limited moth population in the state. As we establish more trap sites, CEW pheromone trap maps will appear in this publication.

At present, the highest nightly pheromone trap catches are as follows:

Beckett 14

Woodstown 12

Berlin 9

Silking Spray Schedules*:

South – 4-5 days

Central – 6 days

North – 7 days

*These recommendations are based on regional catches.

Cole Crops

Imported cabbageworm butterflies (ICW) are active and egg laying is ongoing. Iinfestations of this pest should increase quickly with better weather. Scout plantings weekly. Check 5 consecutive plants each in 10 random locations throughout the planting, paying particular attention to the innermost leaves where ICW often feed. In addition, diamondback moth larvae (DBM) have begun to appear in plantings throughout the state (see photo at right).

Diamondback moth larvae

This very small caterpillar is resistant to synthetic pyrethroid insecticides. In order to obtain adequate control of this pest, insecticides in the IRAC group 5 (Radiant, Entrust (OMRI listed)), or in the IRAC group 28 (Coragen, Exirel) should be used. Consider treating if caterpillars are found on 10% or more plants that are in the 0-9 true leaf stage. From 9-leaf to the early head stage (in broccoli, cauliflower and cabbage) infestations up to 20% may be tolerated. Once heads begin to form, a 5% threshold should be observed to protect the marketable portion of the plant. For leafy greens such as collards and kale, 10% plants infested is the threshold throughout.

Tomatoes

Avoid working in wet tomato fields if at all possible. If bacterial infections are present in this crop, the pathogen may be spread by contact. Bacterial lesions are frequently black in color (see photo at left), and are often present on the newest foliage, whereas early blight lesions and many symptoms of stress related nutritional deficiencies are often found on the older leaves. All tomato plantings should get the full anti-bacterial program found in the recommendations guide. This includes weekly fixed copper sprays (organic and non-organic systems) as well as the use of the immune response activator Actigard, and Quintec, a fungicide with some activity against bacterial pathogens.

Peppers

New pepper plantings are now threatened by the ECB, as moths lay eggs on the underside of pepper leaves (see photo at left). Larvae will hatch and bore into central stems of these small plants, causing the tops of the plants to die. While this is not terminal, it will prevent the production of crown fruit on affected plants. Scout 5 plants each in ten random locations. Check the underside of 2 leaves per plant. If 2 or more ECB eggmasses are found in this sample consider treating with a foliar insecticide or a soil applied insecticide such as Coragen. There are several options listed in the 2016-17 Commercial Vegetable Production Recommendations, including the OMRI approved spinosyn material, Entrust.

Pepper Weevil Update

No pepper weevils were trapped in the past week. So far as is known, there are no infested fields in the region.

Potato leafhopper (PLH)

PLH (see photo at left) have arrived in New Jersey, and are not difficult to find in potato plantings at this time. This pest is also a threat to hops and green beans, and these crops should be checked weekly for the presence of PLH adults and nymphs. As they feed, a toxin is secreted, causing irreversible injury to some the above plants. A downward curl of leaves, followed by yellowing and necrosis are indications of PLH injury. Once this injury is detected in green beans, there is often a considerable loss of pod production. This injury does not occur in peppers, although PLH may feed on this crop. Scout beans weekly, and consider treating if the number of adults plus nymphs exceeds 100 per 20 sweeps during prebloom, 250 per 20 sweeps during bloom, or 500 per 20 sweeps during pod development. If no sweep net is available, consider treating if nymphs are present. This wingless stage of PLH is bright green, and individuals tend to move sideways when disturbed. In potatoes, treatment is suggested if leafhopper counts exceed 1 adult per sweep or 1 nymph per 10 leaves. There are no established thresholds in hops, but the University of Vermont recommends treatment when individuals exceed 2 per leaf in a 25-leaf sample throughout the yard.

Brown Marmorated Stink Bug

To date, only a few brown marmorated stink bugs (BMSB) have been captured in blacklight traps. As catches become more numerous, maps of this pest will appear in this publication.

Field Technicians

Joe Ingerson-Mahar and Kris Holmstrom would like to thank the following field technicians without whom the timely collection and distribution of pest data would not be possible: